Initial Comment:
Would it be possible for the new firmware to be
customisable through either a configuration file (like an
ini file) or possibly an application that could be run on
the host computor when the JB was plugged in?

Theres seems like a lot of indivdual preference for how
various parts should work, so would it be possible to
execute a customisation program which can generate
new .mod files based on user requirements? For
example, have a customisable string that alowed you to
change the boot-up text. Or even use a boot-up graphic?

Also, the program could also alow other programmers to
write plugins that would be compiled into their .mod file.
Such plugins could include visualisation programs, or
alternative menu systems.

This would open up the project to many more
programmers, and would allow limitless expansion.
Plugins could be developed in parrellel with the core
firmware, provided that they are backwards compatable.

This is just an idea that has been kicking obout in my
head, hope its not too far into the impossible....